1. Field of Invention
The invention relates generally to a system and method for sampling a connate fluid subsea. More specifically, the present invention relates generally to a method and device for automatically sampling fluid at a subsea wellhead.
2. Description of Prior Art
Subsea wellbores are formed from the seafloor into subterranean formations lying underneath. Systems for producing oil and gas from subsea wellbores typically include a subsea wellhead assembly set over an opening to the wellbore. Subsea wellheads usually include a high pressure wellhead housing supported in a lower pressure wellhead housing and secured to conductor casing that extends downward past the wellbore opening. Wells are generally lined with one or more casing strings coaxially inserted through, and significantly deeper than, the conductor casing. The casing strings are typically suspended from casing hangers landed in the wellhead housing. One or more tubing strings are usually provided within the innermost casing string; that among other things are used for conveying well fluid produced from the underlying formations. The produced well fluid is typically controlled by a production tree mounted on the upper end of the wellhead housing. The production tree is typically a large, heavy assembly, having a number of valves and controls mounted thereon
Well fluids can be produced from a subsea well after the wellhead assembly is fully installed and the well completed. Produced well fluid is generally routed from the subsea tree to a manifold subsea, where the fluid is combined with fluid from other subsea wells. The combined fluid is then usually transmitted via a main production flow line to above the sea surface for transport to a processing facility. Often, a pump is required for delivering the combined produced fluid from the sea floor to the sea surface. Thus knowledge of the well fluid flow and constituency is desired so the pump and flow line can be adequately designed. While the fluid is often analyzed at sea surface, fluid conditions, e.g. temperature, pressure, are generally different subsea. Moreover, the respective ratios of fluid components, as well as the components themselves, often change over time. As such, a time lag of knowledge of the fluid in the flow lines may occur.